Topband: Problem with compression F connectors on Quad RG-6

[Tom W8JI]

> CATV installers use almost 100% quad shield in order to keep the signals 
> inside and not cause interfering leakage (egress); FCC specs are adamant 
> about that. These specs go back to the 70's. In more recent years the 
> cable also must keep local RFI (ingress) out.

While they do use tape foil shield cables, CATV systems rarely use quad 
shield cables. As a matter of fact I just bought a bunch of drop cable from 
a CATV system, and it is all single foil single braid. This is true for the 
drop, which has a messenger strand, and the house wiring, which is identical 
without a messenger strand.

In the late 70's and early 80's, I was system's engineer at a company that 
had dozens of small cable systems. We inherited some systems near an FM/AM 
station that had a second harmonic on a local TV channel video frequency. 
The former cable system operator had given up, after installing quad shield 
and all sorts of special cables. 100% of their problems were isolated power 
and CATV grounds, letting the AM signal loop through the system, and the 
quad shield developing poor connections letting the FM harmonic in. We 
ripped all that stuff out, and went with normal hardline and good quality 
drop cable, bonded the cable grounds to the entrance and breaker panels, and 
nearly 100% cured the system. We had dumpster load of special cable that was 
nothing but connector headaches.

The standard drop cable is a bonded foil with single braid, it has been that 
way since the late 1970's. The current best grade is "Brightwire" by 
CommScope. Any good cable will far exceed FCC specs without a quad shield. 
Single-foil single-shield "Brightwire" has over 120 dB of external shield 
current to center conductor current isolation on 160 meters, and it gets 
better as you go up in frequency. I can't imagine anyone needing more than 
80 dB isolation outside the house, and maybe 100 dB if it is in a noisy 
house.